I just listen to the song and identify the key signature. From there, I memorize the the lyrics and "fake" the chords (on guitar). If I like it and want to preform it, I will try to add some of the lines and themes I hear on the record. This doesn't work too well if someone has tuned the guitar differently and you haven't. Lately I have discovered chordie.com You can look up a title or artist and read chords and tabs but it is an open unedited site so some contrubutors are way off the mark. It does help speed up the learning process and you can select the "key change" feature and can learn it in different keys.